A tank is usually filled in 8 hours, but due to a leak at the bottom, it takes 2 hours longer to fill. How long will the leak take to empty the full tank on its own?

Explanation

The filling rate without leak is 1/8 per hour. With the leak, it takes 10 hours, so the effective filling rate is 1/10 per hour. Let the leak empty the tank in x hours, so the leak's rate is 1/x. Using the equation: 1/8 - 1/x = 1/10, solving for x gives x = 40 hours.